Auxillary question.

[HAZ]

Hi Guys,
I have a 15ft Cruise Craft Colt Half cab with a 75 hp on the back. I have a heavy duty auxillary bracket and plan on doing some fishing in the Bay and would like know what size auxillary would be suitable to get us back to the ramp if the worst happens. Thanks
HAZ

[Spaniard_King]

I recon a Yearly subscription to ya local VMR would do the trick, save ya a motsa on service and fuel fees. Then theres the weight saving.

Also you are supporting a good cause

Cheers

Garry

[JB]

Yep i agree, bugger the auxillary. Not like ur headin to remote areas of the kimberly or something. Vmr is just a call away ;D

[NQCairns]

Nothing better than trolling home under your own steam [smiley=2thumbsup.gif] a typical aux will only push a boat at displacement speeds until it hits the wall where another 40hp+ is needed to get it on the plane.
As an example a 6hp will push say 8kn and a 15hp will push 9kn.
IMO go with the weight consideration and prop it to reach redline (so that all the hp reaches the water)and even a small engine does a good job in bad weather, 8hp would probably work very well, 6hp would also work fine.

[HAZ]

Thanks guys,
I do like the idea of getting home under my own steam and not tying up the VMR with a just a tow in. I have a fairly new 5hp 2 stroke Mariner and have tried it on it in the Pumicetone passage and it would only just move forward against the current. Should it go a bit better ? It seemed to cavitate even when it was deep in the water. It pushes my 3m tinny along fine but maybe the prob is slipping with the heavier load ? I know 6 to 15 hp all weigh similar but don't want to go to a 15hp if not neccessary.
Thanks

[basserman]

well if you already have a 5hp then thats good but it would be alittle underpowered and may do some damage to the 5hp due to working it too hard IMHO i would go for something like the Tohatsu 9.8hp same weight as a 8hp but same power as a 10hp ;)

[NQCairns]

Haz you will probably need to swap the prop, it should go twice as fast with a prop that lets it rev as long as the current prop is a standard as sold prop.
It will last just as long on the f'glass as on the tinny when proped for each, it's a pain I know but there is now way around it.

[billfisher]

I used my auxillary the other day and I too was getting a lot of cavitation. I noticed that there was a lot of turbulence at the back of the boat. When I dropped the bracket down one notch deeper the cavitation dissappeared completely.

[seabug]

I had an 85hp mercury on the v15 Nautiglass with a 15 as the auxilliary.
I found that if I used the hand throttle it put too much weight at the rear of boat and I could not see over cabin.

I asked about this at the Melb. boat show and the suggestion was made to lock the 15 hp to straight ahead position and lower the 85hp and steer using the standard foward steering position.

This was only partly good as the 85"s leg would not overcome the direct foward thrust of the 15hp and it would not turn easily.

I then fixed vertical pins to the front of both motors (bit of mucking around to get the position right)
And made a connecting bar of half inch gal. pipe with a flat washer welded each end to fit over the pins at front of motors.(this had to be removed before raising the motors)

This worked well
Both motors steered in tandem with steering from the 85"s steering.
Boat would turn in slightly more than its own length.

Hope this helps
Regards
Seabug

[Lucky_Dave76]

I would try a different prop, talk to someone at solas propellors they seem to know what they are doing. I beleive the 5hp is capable of doing the job. I can push my 20 footer that is two ton with a 10hp at nearly 6 knots however it did have a bloody big prop on it ( not particularly good to overprop little motors).
VMR is the best option!
Cheers
Dave

[HAZ]

Thanks for the advice guys. I ended up buying another tinnie on the weekend with a 9.9hp so this should solve my problem. ;D
HAZ